<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box1 {
            width: 300px;
            height: 300px;
            box-shadow: 0 0 5px red;
        }
        
        .box2 {
            width: 300px;
            height: 300px;
            box-shadow: 10px 10px 5px blue;
        }
    </style>
</head>

<body>
    <!-- box - shadow： X轴偏移 Y轴偏移(模糊半径)(扩散半径) 颜色 由内而外(inset) -->
    <div class="box1">

    </div>
    <div class="box2"></div>
</body>

</html>